Les polyedres viraux: armures cristallines des virus d'insectes

Research output: Contribution to journalArticleResearchpeer-review


Viral polyhedroses are very common diseases of insects. They were first identified as leading causes of losses in the silk industry. This heterogeneous group of diseases is characterized by the formation of crystals in infected cells that are called viral polyhedra or occlusion bodies and represent the infectious form of the viruses. Polyhedra have similar role in the infectious cycle of the two groups of viruses responsible for polyhedroses, the cypoviruses a?? members of the Reoviridae family a?? and the Baculoviridae. Polyhedra embed virus particles within infected cells in a robust crystalline matrix that protects viral infectivity after release in the environment. Upon ingestion by a new host, crystals dissolve readily thereby releasing the infectious particles to initiate a new viral cycle. Owing to their unique molecular organization, these atypical infectious forms have long intrigued virologists and biochemists alike. They attracted particular interest because of the in vivo crystallization process and the contrast between rapid release upon ingestion and extreme stability. It is only recently that novel approaches and technologies allowed the structure determination of such tiny crystals by X-ray crystallography. Cypovirus and baculovirus polyhedra share the same role in the virus cycle, the same crystalline lattice with a cubic centered symmetry, and matrix proteins called polyhedrins of similar sizes. However, their building blocks differ by their folds and packing in polyhedra. The two classes of polyhedra therefore harbour distinct molecular architectures and appear to have emerged independently in the virosphere. The role of tyrosine clusters in polyhedra dissolution and the use of molecular arms to achieve in vivo crystallization may thus represent striking cases of convergent evolution. This review summarizes our understanding of viral polyhedra with an emphasis on the recent structural studies. We also provide examples of biotechnological applicat
Original languageEnglish
Pages (from-to)134 - 147
Number of pages14
Issue number3
Publication statusPublished - 2012

Cite this